1. Field of the Invention
This invention relates generally to fluid exchange systems and in particular to those useful in the exchanging of fluids of the types found in motor vehicles and pressurized hydraulic systems. Disclosed herein is a fluid exchange apparatus wherein used hydraulic fluid is exchanged for fresh fluid by interposing the invention in-line with a hydraulic fluid circulation circuit. The exchange apparatus may utilize pressurized spent fluid flow as a fluid power medium to activate the auto-replenishing fluid exchanger system to replace the spent fluid with fresh fluid at equalized flow rates. Alternatively, the exchange apparatus may be externally powered to replace the spent fluid with fresh fluid at equalized flow rates.
2 Related Background Art:
A variety of hydraulic fluid exchange systems are known to those skilled in the art. One early example is the applicant's U.S. Pat. No. 190 5,318,080, which featured a pressure vessel divided into two chambers by a flexible diaphragm (See, FIG. 3). To refill this exchange system with fresh fluid in preparation for the exchange operation, fresh fluid was introduced into one chamber causing the diaphragm to distend and simultaneously force the spent fluid out of the second chamber. A particular characteristic of this device was the limited volumetric capacity of the pressure vessel, as the capacity of fluid exchange was substantially equal to the volume of the contained fresh fluid prior to the exchange process. If the volume of fresh fluid contained in fresh-fluid charged receiver was less than the desired exchange capacity, one would have to interrupt the exchange process upon discharge of the fresh fluid load, recharge the receiver with fresh fluid, and then reinstate the exchange process until the desired fluid capacity was exchanged. Merely increasing the volumetric capacity of the fluid receiver would concomitantly increase manufacturing costs, fluid friction losses, and the overall size of the exchange apparatus. As a result, the efficiency of such a device was limited by the volume of fresh fluid the device was able to contain.
An additional limitation of prior art exchange systems has been the requirement of onboard fluid tanks for holding fresh fluid and used fluid requirements. These tanks increase the overall size and weight of an exchange apparatus, making movement and storage of the fluid exchange apparatus burdensome.